An apparatus for purifying exhaust gas including a carbon remover and three-way catalyst at an exhaust outlet in series has been disclosed in the past, for example, by Patent Document 1. The carbon remover has a catalyst layer for removing carbon, and the three-way catalyst has a three-way catalyst layer for oxidizing and reducing nitrogen oxide NOx, hydro carbon HC, and carbon monoxide CO. Such conventional technique can purify ternary components (NOx, HC, CO) and particulate matter PM containing carbon mainly.
Including the above-mentioned document, the applicant is aware of the following documents as a related art of the present invention.    [Patent Document 1] Japanese Laid-open Utility Model Application Publication No. Hei 4-34426    [Patent Document 2] Japanese Laid-open Utility Model Application Publication No. Sho 64-3017    [Patent Document 3] Japanese Laid-open Patent Application Publication No. Sho 60-43113